The effect of selective visual deprivation on the organization of the retina is to be investigated. Rabbits will be raised inside a striped drum rotating in one direction, and the rest of the time they will be in the dark. After three months or more of this treatment behavioural and physiological tests will be made on their visual system. In particular any changes in the organization of the receptive fields of the ganglion cells in the retina will be noted. Screening pigment migration in the squid retina will also be investigated. In some circumstances this migration appears to be permanent, or at least very long lasting. Experiments will be designed to find the causes of this.